The Turkish prince who defended Constantinople in 1453
Orhan Çelebi (the believed dates of birth and death: 1412 - May 29, 1453) was an Ottoman prince and a claimant for the throne. Orhan was the grandson of Süleyman Çelebi (aka Emîr Süleyman), the eldest son of Sultan Bayezid and the elder brother of Sultan Mehmed I (1413-1421). As the uncle of Sultan Mehmed Fatih ("the Conqueror"), Orhan was his rival and his rights for the throne were pretty convincing.
The Turkish prince who defended Constantinoople
We don't really know much about Orhan Çelebi with the exception of the fact that he and his men joined forces with the defenders of Constantinople in 1453. This fact might seem pretty strange: how come that a top Osman nobleman fights against the Osman army in a hopeless battle defending the doomed city?
There were many foreign volunteers who fought on the city walls. Perhaps, the most known of them is Giovanni Giustianini Longo, an Italian condottiere who brought about 700 heavy armored men to the city. There were also smaller squads of Bocciardi brothers, also from Italy, about 200 archers hired in Crete led by Isidore, the Metropolite of Kyiv and all Ruthenia, a Catalan infantry detachment, and a squad of Don Francisco from Toledo - this nobleman from La Mancha had some Comnenus ancestry and decided to help the city defenders.
But Orhan Çelebi was not a foreigner. Most likely, he lived in Constantinople for all his life. After an unfortunate Ankara battle (1402) when Tamerlan had defeated Orhan's father, Sultan Bayezid, the young Ottoman empire sunk into a bloody havoc of civil war known as Interregnum (1402-1413) when several rightful claimants fought for the throne. Many Orhan's relatives died. Perhaps, he was sent to Constantinople as a young boy, and not only for safety reasons.
The last Romei emperors eagerly tried to play on the opportunity to keep another pretender to the throne in order to influence the affairs and to destabilize the Ottoman monarchy. Sultan Murad II, the father of Mehmed the Conqueror, agreed to annually pay 3000 silver aspras for keeping Orhan in the city. This money was generated by the revenues from the lands and town Orhan owned by the river Strymon (Struma, a river in modern Bulgaria and Greece).
It was a lot of money back then (worth about 10 kg of silver) used to keep Orhan and his bodyguard squad. The emperor retained a certain part of this sum, which was an important source of money as the city grew much poorer at that time. But it looks like the Ottoman authorities often failed to pay timely. The Romei pulled this string many times: pay or we release Orhan - perhaps, too many times, which was one the reasons for Mehmed II to undertake the final and successful attempt to conquer the city in 1453.
However, there is not a single evidence that Orhan Çelebi himself was "up to something". To his credit, he must have never schemed or machinated against the Sultans. Having spent all his life, he obviously thought this city was his home he would have to protect one day, otherwise he would perish like his other relatives who died during the bloody Interregnum. Or, perhaps, he just hated the very idea of being a Sultan. Anyway, he led his soldiers to the walls. The emperor Constantine XI assigned him a part of the outer wall to protect (at Propontis, including the harbour of Eptaskalio), which means that Orhan must have been a good reliable military leader having at least a hundred soldiers under his command.
Between the upper and the nether millstones of history
In the common Turkish historical narrative, Mehmed II is a hero, but Orhan is a traitor. However, we must admit that we can not call a traitor the man who has been kept in actual captivity for all his life, knowing that leaving the city means an immediate death. That is why Orhan and his Turkish soldiers fought to the bitter end - they knew well that there would be no mercy for them.
There are several accounts of his death - interesting enough, all of them telling a different story. Committed sucide, beheaded, or being recognized while trying to escape and then killed, etc. Perhaps, the reason for this discord is that there have not been many people in Mehmed's camp to know Orhan Çelebi by the face, though capturing Orhan was certainly on Mehmed's priority list after the conquest of the city.
We should also bear in mind that there must have been many Orhan's supporters in Mehmed's camp. His court really snaked with a hidden fight between the new bashaws, who had recently converted to Islam (Greeks, Bulgarians, Serbs, Albanians, etc.) and their counterpart, represented by the old Turkish nobility. The reason for them to support Orhan was pretty simple: if Mehmed II fails to conquer Constantinople and dies, then the next Sultan will be Orhan! This topic is worth a separate research, but for now we should stop assuming that Orhan's hidden supporters could have been found among the old Turkish aristocracy. Some of these people were beheaded soon after the conquest of the city, which also raises flags, doesn't it?
Did he really die in 1453?
This brings us to an interesting conclusion - that Orhan Çelebi did have a small chance to escape, perhaps with some of his surviving men, through the efforts of his secret devotees and making use of the fact that his face remained unknown by the enemy. But anyway, the figure and the fate of this lesser known Ottoman prince is very interesting, if not odd, especially from the point of view of what a noble man should do when he is stuck between the upper and the nether millstones of history.
On the top screenshot: Yalçın Özbek as Orhan Çelebi in the feature documentary film "Parateichion"